<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>虚线setLineDash  </title>
</head>
<body>
<canvas id="canvas" width="200" height="200"></canvas>
<script>
  var ctx = document.getElementById('canvas').getContext('2d');// Create gradients
  var lingrad = ctx.createLinearGradient(0,0,0,150);
  lingrad.addColorStop(0, '#00ABEB');
  lingrad.addColorStop(0.5, '#fff');
  lingrad.addColorStop(0.5, '#26C000');
  lingrad.addColorStop(1, '#fff');

  var lingrad2 = ctx.createLinearGradient(0,50,0,95);
  lingrad2.addColorStop(0.5, '#000');
  lingrad2.addColorStop(1, 'rgba(0,0,0,0)');

  // assign gradients to fill and stroke styles
  ctx.fillStyle = lingrad;
  ctx.strokeStyle = lingrad2;

  // draw shapes
  ctx.fillRect(10,10,130,130);
  ctx.strokeRect(50,50,50,50);

</script>
</body>
</html>